1. Field of Invention
The present invention relates to a helicon plasma source, more particularly to a helicon plasma source having at least one permanent magnet, and to corresponding methods of plasma processing.
2. Discussion of Related Art
Helicon sources were invented around 1970 in Australia by R. W. Boswell1. Chen's group at UCLA demonstrated by careful measurements2 that an earlier proposed Landau damping mechanism3 was not the mechanism responsible for the extraordinary efficiency of the helicon sources in producing high plasma density. Early work on helicon waves and sources has been summarized in a book chapter4 and in two review articles5,6. Commercial helicon reactors for etching of and deposition on semiconductor chips have been manufactured by Alcatel in France, Lucas Labs7 in the San Francisco area, and PMT (now Trikon) in Chatsworth, Calif.7A 
The injection of plasma from a single discharge tube, excited by a half helical antenna8,9, into a large plenum was studied by Chen et al.10 Surrounding the single discharge tube with a small solenoid was found to be inadequate, because the shape of the magnetic field was such that the particles in the plasma tended to impact the walls of the discharge tube, rather than traveling, that is, rather than being injected, into the plenum. This problem was resolved by replacing the solenoid with a large diameter electromagnet, which changed the shape of the magnetic field such that the magnetic field lines were substantially straight in passing from the discharge tube into the plenum. Because of the straight magnetic field lines, the particles in the plasma were injected into the plenum.
However, the use of a large electromagnet for generating an electromagnetic field with straight field lines for the injection of plasma from a discharge tube into a large plenum presents several problems for incorporation into a commercial helicon plasma source. A large electromagnet has a large electrical power requirement, and can require active cooling, for example, forced circulation of water or air. An electromagnet can be larger and heavier than a permanent magnet producing a magnetic field of similar magnitude and would be impractical for meter-size substrates. There thus remains a need for more comp act, extendable, and economical helicon plasma sources.